code: def _calculate_n_plus(out_index, l, k, layer, input_layer_block):
      if l == k:
          return 0
      x_l_index = layer.input_index_mapper(
          layer.get_input_index(out_index, l)
      )
      x_k_index = layer.input_index_mapper(
          layer.get_input_index(out_index, k)
      )
      return max(
          x_k_bound - x_l_bound
          for x_k_bound in input_layer_block.z[x_k_index].bounds
          for x_l_bound in input_layer_block.z[x_l_index].bounds
      )
  
file_path: OMLT/src/omlt/neuralnet/layers/full_space.py
imports: import numpy
  import pyomo.environ
  from pyomo.contrib.fbbt.fbbt import compute_bounds_on_expr
  from omlt.neuralnet.activations import NON_INCREASING_ACTIVATIONS
  from omlt.neuralnet.layer import ConvLayer2D, IndexMapper, PoolingLayer2D
label_desc: Use image node_id 4 for calling a global function with example usage: _calculate_n_plus(out_index, l, k, layer, input_layer_block) and returns: max, int